1. Technical Field
The present disclosure relates to color reproduction. More particularly, the present disclosure relates to color reproduction of arbitrary colors in a predetermined workflow. The present disclosure also relates to error analysis with respect to color reproduction in a predetermined workflow. In exemplary embodiments, the predetermined workflow is a two-stage workflow including a proofing stage and a production stage.
2. Background Art
The printing of arbitrary colors (e.g., spot colors) within a complex printing process is a common requirement. It is not unusual for a particular printing assignment, for example, an advertisement, packaging, etc., to contain both photographic and brand-specific colors. Notably, brand-specific colors are often selected without regard to image content. Examples of brand-specific colors include, but are not limited to, logo colors, trademark colors, background colors, for example, on broad areas of packaging, for highlighting other brand-specific colors, etc.
In many cases, particularly with respect to logos and trademarks, a same design must be accurately and uniformly reproduced across various types of media. A modern example of this is the use of “automobile wraps,” wherein an automobile (or other moving vehicle) is “wrapped” with advertising content (commonplace, for example, with racing vehicles and with local commercial vehicles). In these instances, it is often a requirement that the reproduced colors match the target colors, for example, the colors of an advertised product, logo, trademark, etc., very closely.
The difficulties in achieving color uniformity are apparent from any process for reproducing colors. For example, one may start with a physical reference. In the case of many color systems, this is a physical guidebook, for example, the Pantone® PMS+ guide. In some cases, however, a brand may use a particular specimen as a physical reference for a brand-color. In any case, the perceived physical reference is, at any given moment, subjected to viewing conditions. This introduces a degree of variability in that the physical reference may be perceived differently under different viewing conditions. Next an abstract color is defined linking the color of the physical reference to a colorimetric measurement, such as CIELAB of the color, for example, using a colorimeter or spectrophotometer, and/or a formulation color such as CMYK. The abstract color is normally defined colorimetrically and/or spectrally. The abstract color may then be rendered, for example, printed or displayed. Once again, the rendered color is subjected to a set of viewing conditions resulting in a perceived rendered color.
In general, the goal of any color reproduction process is to ensure that a color which is selected as a perceived color of a physical guide is visually reproduced by the rendered color on a selected media (sometimes for a predetermined set of viewing conditions). One challenge is therefore to reproduce an arbitrary color in a reproduction system that typically reproduces or is required to reproduce other color data in predetermined fashion (for example, where processing cannot be altered for the sake of the arbitrary color). In many situations, a physical reference color may not be reproducible within the limitations of the selected color workflow (known as an “out-of-gamut color”). Conventional printing systems and methods often have difficulties reproducing out-of-gamut colors. These and other difficulties are addressed by the systems and methods of the present disclosure.
In addition to benefits associated with the disclosed systems and methods for reproduction of arbitrary colors in a work flow, the present disclosure also improves on systems and methods for analyzing errors in a color reproduction process. A typical workflow, for example, for a print press, may generally involve a two-stage workflow including a proofing stage and a production stage. The proofing process advantageously enables a customer to visualize how a finished printed product will look. Proofing can either involve a physical proof (for example, using a printing proofer, typically a large format printer, separate from the production stage) or a virtual proof (for example, using a display). In either case, the generation of the proof involves a color reproduction process. A customer may advantageously use the proofing stage to fine-tune the desired appearance of the printed product. Once a customer is satisfied with the proof, the workflow switches to the production stage. The production stage may typically include a formulation process relating to ink output and a press process relating to a press output. Notably, both the formulation of the ink output and the printing of the press output involve a color reproduction process. The reason for the two-stage workflow is that, due to set-up costs, proofing via the production stage would be cost-prohibitive. The present disclosure addresses some of the difficulties in integrating error analysis into a two-stage workflow such as described above.